What are the topics that I should read within these 20 days so that I can clear JEE advanced in a decent way.Thereby getting a core branch

Hello,

First of all congratulations on being eligible for taking JEE Advanced exam. During this time till JEE Advanced, I would suggest you to practice more and more questions from different topics and note down your mistakes. You should try not to repeat those same mistakes in similar questions. You must have read all the topics by far. So you may now focus on your weak topics and practice a lot from your strong topics. Try to solve previous year questions too.

In Physics, you should practice a lot of Electrostatics and Modern Physics questions. In Maths, do Calculus very well along with Vectors and Three-dimensional geometry. In Chemistry, you should study every topic very well. You must learn all the mechanisms of Organic Chemistry. Please note that every topic of every subject is important. The above mentioned topics are the ones with high weightage.

All the best!